The present invention relates to a common file system for a plurality of data processors and, more particularly, to a system for controlling use of a file when data in the file is commonly used in units of blocks or exclusive use of files for a plurality of data processors.
In a system wherein a plurality of data processors use files in common in units of blocks, when one of the plurality of data processors updates one block, the block is update-locked by a transaction task, and no access request with respect to the block from other data processors is accepted.
In a conventional system wherein an update history file is provided for each task processing program group, if a data processor updating a file is abnormally stopped, a block which is locked is recovered to a state before updating by a file updating unit in accordance with all the update history files corresponding to a transaction task being processed in the abnormally stopped data processor, and then closing with respect to the block being released. That is, closing of the block which is update-locked by the transaction task being processed in the abnormally stopped data processor is not released immediately after completion of file recovery by one update history file but is released after completion of file recovery processing by all the update history files. Therefore, if an access request with respect to the recovered block from other data processors exists before the file recovery processing by all the update history files is completed, access processing cannot be executed until the file recovery processing by all the update history files is completed.